The collection and disposal of household-type garbage present various important problems. There is, on the one hand, nuisance and pollution and, on the other, waste of raw materials which are destroyed by conventional techniques.
Two methods are currently practiced. In one, household-type garbage is spread in layers 2.50 m thick and covered up with earth; in the other method, it is incinerated.
The first solution causes underground seepage whose composition and spread are not controlled, which represents a danger for the water table and streams.
The second solution presents the inconvenience of producing ashes whose volume is of the order of 30 to 40% of the burned materials. These ashes can be reused only with difficulty and their destruction therefore presents problems. This destruction can be effected only by burial in the ground, whereupon the ground becomes unsuitable either for agriculture or for construction. In addition, the total amount of methane gas used both in industry and in the home comes at the present time from the exploitation of deposits of natural gas. Depending on the location of the deposits, the composition of natural gases varies. Some gases, such as that of LACQ (a site in France), contain constituents which must be entirely eliminated. This operation is costly and heavily influences the sales price. Gas from LACQ, as used, has a calorific power of 9,960 Kcal/m.sup.3. Other gases, such as that of Groninger (in the Netherlands), have noncombustible constituents such as carbon dioxide and nitrogen. These two constituents are not eliminated so as not to increase production cost, but their presence influences unfavorably the calorific power which is of the order of 8,400 kcal/m.sup.3. Other gases, such as that of HASSI R'MEL (a site in ALGERIA), have an ideal composition which, besides the fact that they do not require prior treatment, confers to them a high calorific power of the order of 10,700 kcal/m.sup.3. Cases like the latter are, however, very rare.